Inhibition of BACH1 (FANCJ) helicase by backbone discontinuity is overcome by increased motor ATPase or length of loading strand
Gupta, Rigu ; Sharma, Sudha ; Doherty, Kevin M. ; Sommers, Joshua A. ; Cantor, Sharon B. ; Brosh, Robert M.
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Keywords
Amino Acid Sequence
Basic-Leucine Zipper Transcription Factors
Catalysis
DNA
DNA Helicases
DNA, Single-Stranded
Fanconi Anemia Complementation Group
Proteins
Humans
Molecular Sequence Data
Polymorphism, Genetic
Protein Structure, Tertiary
Cancer Biology
Enzymes and Coenzymes
Neoplasms
Skin and Connective Tissue Diseases
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Abstract
The BRCA1 associated C-terminal helicase (BACH1) associated with breast cancer has been implicated in double strand break (DSB) repair. More recently, BACH1 (FANCJ) has been genetically linked to the chromosomal instability disorder Fanconi Anemia (FA). Understanding the roles of BACH1 in cellular DNA metabolism and how BACH1 dysfunction leads to tumorigenesis requires a comprehensive investigation of its catalytic mechanism and molecular functions in DNA repair. In this study, we have determined that BACH1 helicase contacts with both the translocating and the non-translocating strands of the duplex are critical for its ability to track along the sugar phosphate backbone and unwind dsDNA. An increased motor ATPase of a BACH1 helicase domain variant (M299I) enabled the helicase to unwind the backbone-modified DNA substrate in a more proficient manner. Alternatively, increasing the length of the 5' tail of the DNA substrate allowed BACH1 to overcome the backbone discontinuity, suggesting that BACH1 loading mechanism is critical for its ability to unwind damaged DNA molecules.
Source
Nucleic Acids Res. 2006;34(22):6673-83. Epub 2006 Dec 1. Link to article on publisher's site